Method of and an apparatus for determining the cross-section of products of the textile industry, especially that of yarns, rovings and slivers

ABSTRACT

Method and apparatus for determining the cross-section of textile products including means for generating a sound field at least partially within a resonator and means for measuring the phase disturbance in said sound field created by the passage of a textile product therethrough.

United States Patent [191 3,750,461 Felix Aug. 7, 1973 METHOD OF AND AN APPARATUS FOR DETERMINING THE CROSS-SECTION OF PRODUCTS OF THE TEXTILE INDUSTRY, ESPECIALLY THAT OlF YARNS, ROVINGS AND SLIVERS Inventor:

US. Cll. 73/67.5, 73/69 Int. Cl. Cilln 29/00 Field of Search 73/67.l, 67.2, 67.5 R,

References Cited UNITED STATES PATENTS Demars 73/160 X FOREIGN PATENTS OR APPLICATIONS 7l0,l24 6/1954 Great Britain 73/69 Primary Examiner-James J. Gill Attorney-Craig, Antonelli & Hill 22 Claims, 9 Drawing; Figures PATENTED MIG H975 SHEET 1 OF 2 Fig.1

MTORNEYS METHOD OF AND AN APPARATUS FOR DETERMINING THE CROSS-SECTION 01F PRODUCTS OF THE TEXTILE INDUSTRY,

ESPECIALLY THAT F YARNS, ROVINGS AND SLIVERS The present invention relates generally to article measuring, and more particularly to a method of and an apparatus for determining the cross-section of products of the textile industry, especially that of yarns, rovings and slivers.

There is disclosed in copending application, Ser. No. 153,764, filed June 16, 1971, a method of and an apparatus for determining the cross-section of products of the textile industry, especially that of yarns, rovings and slivers, in which the textile product to be tested, on passing through a sound field consisting of at least one sound generator and at least one sound pickup, produces changes in the transit-time of the sound waves, which changes are converted into signals in a transittime discriminator.

The principle behind this invention has now been further improved by virtue of the fact that the sound field existing between the sound generator and the sound pickup is generated within resonators tuned at least approximately to the working frequency or to one of its harmonics in order to amplify the changes in transit time attributable to the textile product. The associated apparatus comprises resonators which are tuned at least approximately to the working frequency or to one of its harmonics.

In its basic form, a resonator is formed with the dis tance between the sound generator and the sound pickup measured to half the wave length of the working frequency.

In one improved embodiment, the resonators used form a resonance chamber measured at least approximately to one quarter of the wave length of the working frequency, being associated either with the sound generator or with the sound pickup or with both.

The greatest influence of the textile product upon the transit time of the sound waves is obtained in cases where the textile product travels through a point at least approximately where the maximum velocity (minimum pressure) or minimum velocity (maximum pressure) of the stationary wave is present in the resonator.

The invention is described in detail in the following with reference to the accompanying drawings, wherein:

FIG. 11 is a phase diagram;

FIG. 2a shows a sound field tuned to half the wave length and FIG. 2b shows the pressure and velocity pattern of the sound field;

FIG. 3 shows the arrangement according to FIG. I with a textile product oriented symmetrically in the sound field;

FIG. 4 shows the arrangement according to FIG. I with a textile product oriented asymmetrically in the sound field;

FIGS. 5 and 6 show arrangements with asymmetrically arranged resonance chambers;

FIG. 7 shows an arrangement with symmetrically arranged resonance chambers; and

FIG. 8 is a schematic diagram showing a regulating system for compensating for troublesome influences in the sound field.

FIG. 11 in the form ofa graph shows the pattern 30 of the phase displacement d: and the change in transit time as a function of the standardized frequency and wave length, respectively. This behavior is known per se from the theory of oscillation. The steepness of the phase displacement, as determined by the angle of the tangent 32 at the reversing point 31, is greater or smaller in dependence upon the sharpness of resonance, which equals the quality of the resonant circuits; in other words, the tangent 32 is steep with high sharpness of resonance and less steep with lower resonance sharpness, as represented by tangent 33. If now the resonance conditions are disturbed by the introduction of a material, for example a textile product in the form of a yarn, roving or sliver, into the sound field, the transittime conditions for the sound field vibrating at least approximately in resonance are changed, giving rise to considerable phase displacements in the sound pickup. These phase displacements can be evaluated into signals which correspond to the quantity of material introduced into the sound field. Where the arrangement has a high sharpness of resonance, it is possible for even very small quantities of material to produce signals that can be effectively measured.

According to FIG. 2a, the sound generator 10 and the sound pickup 112, or more exactly their pressure and velocity-generating elements, are spaced by a distance of M2, which equals half the wave length of the working frequency. Providing the boundaries of the sound field are formed by reflecting surfaces 118 and 19, this, as already known, promotes the formation of standing waves, as seen in FIG. 2b, in which on the one hand the velocity of the moved air and, on the other hand, its pressure remain locally constant.

If these stationary waves are disturbed, for example by the introduction of a textile product 15 into the sound field, as seen in FIG. 3, a displacement in the transit time occurs and the sound pick-up 112 receives a sound signal which is displaced in phase in relation to the undisturbed state. This change in the transit time will be more or less considerable, depending upon the quantity of textile product introduced.

Differences also occur in the size of the change in transit time for a constant interference quantity with regard to the point at which the stationary wave is dis-. turbed. These changes in transit time are most pro nounced in cases where the disturbance occurs either in a vibration node or in an antinode. In the stationary wave, vibration nodes and antinodes are formed at the reflecting surfaces 118 and 19 on the one hand and in the plane half way between them on the other hand. In order to evaluate this phenomenon, this means that the textile product 15 has to be guided either with advantage in the middle between the reflecting surfaces 18 and 19 (FIG. 3) or directly along one of these surfaces (FIG. 4).

The development of stationary waves is made very much easier by the use of resonance chambers. It is possible in this way not only to avoid need to surround the sound generator 10 and the sound pickup 12 by theoretically infinitely large reflecting surfaces, but the sound energy can also be concentrated in the area through which the material passes.

FIG. 5 shows a sound generator 10 with a resonance chamber 20 which is arranged opposite the sound pickup 12 mounted in the reflecting surface 19. The resonance chamber 20 is advantageously tuned to one quarter of the wave length of the working frequency. FIG. 6 shows the inverse arrangement with a resonance chamber 22 of the same length surrounding the sound pickup 12.

FIG. 7 illustrates a sound field which spreads out between two resonance chambers 20 and 22, one of which surrounds the sound generator and the other surrounds the sound pickup 12. The gain in the detected changes in transit time is at its greatest in this arrangement because the openings arranged opposite one another of the resonance chambers and 22 only cause a small stray field and most of the sound energy passes over from one resonance chamber to the other. The effect of the resonance chamber can be further controlled by virtue of the fact that the size of the change in transit time attributable to the textile product 15 is governed by its resonance quality.

Various means can be used for eliminating outside influences which affect the transit time, the resonance frequency or other factors, and hence, render more accurate the signal resulting from the phase displacements. In one preferred case, a reference system is required, being subjected to the same outside influences as the measuring sound field so that all the parameters affecting the transit time and the sound velocity become simultaneously active in both systems. A sound field which is unaffected by the textile product to be tested is used for this purpose. This system supplies the reference value with which the signal supplied by the measuring system is compared.

In another advantageous embodiment for compensating outside influences, the frequency of the sound generator is controlled in such a way that the phase position between the sound generator and the sound pickup remains constant. To this end, a control signal U is generated (FIG. 8) through a phase discriminator 13 in a reference sound field comprising a sound generator 10' and a sound pickup 16. The output of the phase discriminator l3 acts on the oscillator 11 for the sound generator 10 in such a way that, at any given moment, the frequency corresponds to the conditions required by the distance between the generator and pickup.

In order to obtain a phase displacement which is symmetrical with regard to the fluctuations in the crosssection of the textile product 15 in cases where the cross-section of the textile product increases or decreases, it is further of advantage to tune the frequency of the empty sound field to a value, such as at point 35 (FIG. I), which is situated at the boundary of the substantially linear portion of the phase characteristic. Through the introduction of the textile product 15 to be tested, the working point is displaced along the phase curve towards the reversing point 31 and beyond it so that the positive and negative deviations, fluctuating around an average value of the cross-section, from this average value produce at least substantially equal phase displacements.

The resonance conditions can also be achieved in practice by adapting the geometrical dimensions of the resonance chambers to one of the harmonics of the working frequency.

What is claimed is:

l. A method of determining the cross-section of products of the textile industry, especially yarns, rovings and slivers, comprising generating a sound field within a main resonator tuned approximately to the working frequency or one of its harmonics of the sound to thereby create a standing wave therein,

passing the textile product through the sound field at a predetermined location, and

measuring the disturbance in the resonance conditions in said main resonator produced by the introduction of the textile product into the sound field. 2. A method as defined in claim 1 wherein the textile product is guided at least approximately in the vicinity of the maximum velocity of the standing wave generated in said resonator.

3. A method as defined in claim 1 wherein the textile product is guided at least approximately in the vicinity of the minimum pressure of the standing wave generated in said resonator.

4. A method as defined in claim 1 wherein the textile product is guided at least approximately in the vicinity of the minimum velocity of the standing wave generated in said resonator.

5. A method as defined in claim 1 wherein the textile product is guided at least approximately in the vicinity of the maximum pressure of the standing wave generated in said resonator.

6. A method as defined in claim 1 wherein said sound field is generated by a sound generator and measured by a sound pickup spaced by a distance which corresponds at least approximately to half the wave length of the working frequency.

7. A method as defined in claim 1 wherein said resonator is tuned at least approximately to one-fourth the wave length of the working frequency and is in communication with said generator.

8. A method as defined in claim 1 wherein said resonator is tuned at least approximately to one-fourth the wave length of the working frequency and is in communication with said pickup.

9. A method as described in claim 1, further comprising generating a second sound field within a second resonator at the same working frequency and under the same conditions as said main resonator,

measuring the resonance conditions in said second resonator, and

comparing the measured resonance conditions of said main resonator with the measured resonance conditions of said second resonator.

10. A method as described in claim 9, wherein said step of comparing is performed by regulating the frequency of said sound field in response to the measured resonance conditions of said second resonator.

l 1. An apparatus for determining the cross-section of products of the textile industry, especially yarns, rovings and slivers, comprising means for generating sound at a preselected working frequency,

sound pickup means disposed in spaced relationship to said sound generating means,

at least one hollow resonator cavity positioned between said sound generating means and said sound pickup means and being tuned to said working frequency or a harmonic thereof, said sound generating means establishing a sound field within said resonator cavity, to thereby create a standing wave therein, and

means for guiding a textile product through said hollow resonator cavity.

12. An apparatus as defined in claim 11 wherein said sound field is tuned at least approximately to half the wave length of the working frequency or one of its harmonies.

113. An apparatus as defined in claim 12 wherein said means for guiding a textile product passes the product in the vicinity of the maximum velocity of the standing wave.

114. An apparatus as defined in claim 12 wherein said means for guiding a textile product passes the product in the vicinity of the minimum pressure of the standing wave.

15. An apparatus as defined in claim 12 wherein said means for guiding a textile product passes the product in the vicinity of the maximum pressure of the standing wave.

16. An apparatus as defined in claim 12 wherein said means for guiding a textile product passes the product in the vicinity of the minimum velocity of the standing wave.

17. An apparatus as defined in claim 12 wherein said resonator is tuned at least approximately to one-fourth the wave length of the working frequency or one of its harmonics and is disposed with one end at said sound generating means.

18. An apparatus as defined in claim 12 wherein said resonator is tuned at least approximately to one-fourth the wave length of the working frequency or one of its harmonics and is disposed with one end at said sound pickup means.

19. An apparatus as defined in claim 12 including first and second resonators tuned approximately to one-fourth the wave length of the working frequency or one of its harmonics, said first resonator having one end disposed at said sound generating means and said second resonator being coextensive with said first resonator and having one end at said sound pickup means with a space for passage of said textile product being provided between said resonators.

-20. An apparatus as defined in claim 12, further including reference sound generating means for generating a sound field in a second resonator at said working frequency, reference sound pickup means disposed in spaced relationship to said reference sound generating means, and comparison means for comparing the measured resonance conditions of said resonator with the measured resonance conditions of said second resonator.

21. An apparatus as defined in claim 20 wherein said comparison means includes a phase discriminator connected between said reference sound pickup means and said sound generating means for regulating the fre quency of the sound field in said resonator in accordance with the measured resonance conditions in said second resonator.

22. An apparatus as defined in claim 21 wherein the frequency of said reference sound is adjusted to provide operation on the phase characteristic of the sound field at a point situated at the boundary of the substantially linear portion thereof.

a t t: t 1k v UNITED STATES PATENT OFFICE @ERTIFICATE OF CQRRECTION Pa nt N 3. 750. 461 D te August 7, 1973 Inventor(s) Ernst FQliX It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Priority data omitted. Should read:

-Switzerland 9191/70 June 16, 1970-- Signed and sealed this 18th day of December 1973.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents 1 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,750,461 Dated August7, 1973 Inventor(s) Ernst FEZliX It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Priority data omitted. Should read:

-Switzrlend I 9191/70 June 16, 1970-- Signed and Sealed this 18th day of December 1973.

(SEAL) Attest;

EDWARD M. FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patent 

1. A method of determining the cross-section of products of the textile industry, especially yarns, rovings and slivers, comprising generating a sound field within a main resonator tuned approximately to the working frequency or one of its harmonics of the sound to thereby create a standing wave therein, passing the textile product through the sound field at a predetermined location, and measuring the disturbance in the resonance conditions in said main resonator produced by the introduction of the textile product into the sound field.
 2. A method as defined in claim 1 wherein the textile product is guided at least approximately in the vicinity of the maximum velocity of the standing wave generated in said resonator.
 3. A method as defined in claim 1 wherein the textile product is guided at least approximately in the vicinity of the minimum pressure of the standing wave generated in said resonator.
 4. A method as defined in claim 1 wherein the textile product is guided at least approximately in the vicinity of the minimum velocity of the standing wave generated in said resonator.
 5. A method as defined in claim 1 wherein the textile product is guided at least approximately in the vicinity of the maximum pressure of the standing wave generated in said resonator.
 6. A method as defined in claim 1 wherein said sound field is generated by a sound generator and measured by a sound pickup spaced by a distance which corresponds at least approximately to half the wave length of the working frequency.
 7. A method as defined in claim 1 wherein said resonator is tuned at least approximately tO one-fourth the wave length of the working frequency and is in communication with said generator.
 8. A method as defined in claim 1 wherein said resonator is tuned at least approximately to one-fourth the wave length of the working frequency and is in communication with said pickup.
 9. A method as described in claim 1, further comprising generating a second sound field within a second resonator at the same working frequency and under the same conditions as said main resonator, measuring the resonance conditions in said second resonator, and comparing the measured resonance conditions of said main resonator with the measured resonance conditions of said second resonator.
 10. A method as described in claim 9, wherein said step of comparing is performed by regulating the frequency of said sound field in response to the measured resonance conditions of said second resonator.
 11. An apparatus for determining the cross-section of products of the textile industry, especially yarns, rovings and slivers, comprising means for generating sound at a preselected working frequency, sound pickup means disposed in spaced relationship to said sound generating means, at least one hollow resonator cavity positioned between said sound generating means and said sound pickup means and being tuned to said working frequency or a harmonic thereof, said sound generating means establishing a sound field within said resonator cavity, to thereby create a standing wave therein, and means for guiding a textile product through said hollow resonator cavity.
 12. An apparatus as defined in claim 11 wherein said sound field is tuned at least approximately to half the wave length of the working frequency or one of its harmonics.
 13. An apparatus as defined in claim 12 wherein said means for guiding a textile product passes the product in the vicinity of the maximum velocity of the standing wave.
 14. An apparatus as defined in claim 12 wherein said means for guiding a textile product passes the product in the vicinity of the minimum pressure of the standing wave.
 15. An apparatus as defined in claim 12 wherein said means for guiding a textile product passes the product in the vicinity of the maximum pressure of the standing wave.
 16. An apparatus as defined in claim 12 wherein said means for guiding a textile product passes the product in the vicinity of the minimum velocity of the standing wave.
 17. An apparatus as defined in claim 12 wherein said resonator is tuned at least approximately to one-fourth the wave length of the working frequency or one of its harmonics and is disposed with one end at said sound generating means.
 18. An apparatus as defined in claim 12 wherein said resonator is tuned at least approximately to one-fourth the wave length of the working frequency or one of its harmonics and is disposed with one end at said sound pickup means.
 19. An apparatus as defined in claim 12 including first and second resonators tuned approximately to one-fourth the wave length of the working frequency or one of its harmonics, said first resonator having one end disposed at said sound generating means and said second resonator being coextensive with said first resonator and having one end at said sound pickup means with a space for passage of said textile product being provided between said resonators.
 20. An apparatus as defined in claim 12, further including reference sound generating means for generating a sound field in a second resonator at said working frequency, reference sound pickup means disposed in spaced relationship to said reference sound generating means, and comparison means for comparing the measured resonance conditions of said resonator with the measured resonance conditions of said second resonator.
 21. An apparatus as defined in claim 20 wherein said comparison means includes a phase discriminator connected between said reference sound pickup means and said sound generating means for regulating the frequency of thE sound field in said resonator in accordance with the measured resonance conditions in said second resonator.
 22. An apparatus as defined in claim 21 wherein the frequency of said reference sound is adjusted to provide operation on the phase characteristic of the sound field at a point situated at the boundary of the substantially linear portion thereof. 